Key Topics serve as a nexus between research groups in different research areas. We have taken into account the need for intensive communication between different research groups by organizing a series of those Key Topics that will foster interaction throughout the cluster: each Key Topic is being organized and led by a particular research group. This “lead project/group” is responsible for fostering exchanges between the different research areas and synthesizing the different concepts applied to one and the same historical phenomenon as seen from quite different disciplinary perspectives. Some of these themes are organized by junior research groups. The architecture of these key topic units is also open to allow for the addition of new key topics as warranted by the ongoing work of the cluster. At present, there are six Key Topics: